IACR paper details

In a proxy signature scheme, a potential signer delegates his
capabilities to a proxy signer, who can sign documents on behalf of
him. The recipient of the signature verifies both identities: that of
the delegator and that of the proxy signer. There are many proposals
of proxy signature schemes, but security of them has not been considered
in a formal way until the appearance of the work by Boldyreva et al.
If the entities which take part in a proxy signature scheme are formed
by sets of participants, then we refer to it as a fully distributed
proxy signature scheme.
In this work, we extend the security definitions introduced by
Boldyreva et al. to the scenario of fully distributed proxy signature
schemes, and we propose a specific scheme which is secure in this new
model.